In all cosmetic raw materials, humectants occupy a very important position. On the one hand, almost all cosmetic formulas are inseparable from humectants, which are one of the basic substances that make up cosmetics; on the other hand, humectants play an important role in the function and quality of cosmetics. People are no longer satisfied with grease skin care products of the past, but some refreshing moisturizing products.
Humectants are a class of hygroscopic compounds that absorb moisture from moist air. Humectants retain moisture by absorbing and retaining water. In the traditional cosmetics, raw materials having moisturizing functions are mainly divided into two categories, one type is humectant, such as glycerol and so on, which retains moisture through moisture absorption; the other type is nonpolar humectant, such as Vaseline, white mineral oil and so on, which forms a sealing oil film on the surface so as to reduce vaporization of moisture from the surface of skin, and moisture of underlying tissue can diffuse into the stratum corneum to further hydrate the stratum corneum to achieve the effect of retaining moisture.
In traditional cosmetics field, people unilaterally believe that dry skin is due to the lack of lipids on the surface of skin. Studies have shown that only applying grease to the surface of the skin does not make the skin soft. The real cause of dry skin is insufficient water in the stratum corneum. The stratum corneum controls the moisture of the outer skin and acts as a barrier. In order to maintain the skin's water balance, the stratum corneum should maintain a certain amount of moisture to counter the humidity changes of the external environment. To make the skin smooth, soft and elastic, the skin must maintain a certain moisture content, usually the moisture content of skin should be maintained at 10%˜20%.
The deficiencies of conventional cosmetics for moisturizing are as follows:
1. Most of the moisturizing cosmetics on the market merely hydrate and retain moisture of the skin with polyol, such as glycerol and propanediol, but do not take fully consideration on locking moisture of the skin and long term nourishment.
2. Traditional cosmetics use non-polar humectants such as Vaseline, white mineral oil and the like, which form a layer of sealing oil film on the surface, leading to poor breathability of skin. Due to excessive oiliness, these products have poor feelings of use, increase the burden on the oily skin, which also may clog pores and lead to the risk of acne on skin.
3. Although some cosmetics on the market developed new technology on the basis of hydrating and retaining moisture, there is few cosmetic that aims at repairing the skin barrier in an all-round way and improving self-repairing and dynamic balance of hydrating and retaining moisture of the skin barrier.
4. In traditional cosmetics, some functional moisturizing ingredients are added, but the promotion of percutaneous absorption is not fully considered, so that many functional moisturizing ingredients stay on the surface of the skin and cannot enter the stratum corneum of skin to effectively stimulate the skin's moisture retaining ability. Under this condition, the skin cannot retain moisture for a long time, resulting in a waste of the cost of the functional ingredients of cosmetics.
Thus, moisturizing cosmetics having good moisture retaining properties is in need of being further developed.